Known tape printing apparatus of the type with which the present invention is concerned are disclosed in EP-A-322918 and EP-A-322919 (Brother Kogyo Kabushiki Kaisha) and EP-A-267890 (Varitronic). The printers each include a printing device having a cassette receiving bay for receiving a cassette or tape holding case. In EP-A-267890, the tape holding case houses an ink ribbon and a substrate tape, the latter comprising an upper image receiving layer secured to a backing layer by an adhesive. In EP-A-322918 and EP-A-322919, the tape holding case houses an ink ribbon, a transparent image receiving tape and a double sided adhesive tape which is secured at one of its adhesive coated sides to the image tape after printing and which has a backing layer peelable from its other adhesive coated side. With both these apparatus, the image transfer medium (ink ribbon) and the image receiving tape (substrate) are in the same cassette.
It has also beer proposed by the present applicants in, for example, EP-A-578372 to house the ink ribbon and the substrate tape in separate cassettes.
In all of these cases, the image receiving tape passes in overlap with the ink ribbon to a print zone consisting of a fixed print head and a platen against which the print head can be pressed to cause an image to transfer from the ink ribbon to the image receiving tape. There are many ways of doing this, including dry lettering or dry film impression, but the most usual way currently is by thermal printing where the print head is heated and the heat causes ink from the ink ribbon to be transferred to the image receiving tape.
The devices of the type described above are provided with a keyboard which enables a user to enter characters, symbols and the like to form an image to be printed by the tape printer. The keyboard usually has text character keys and number keys for entering letters and number keys respectively, plus some function keys which, among other things, operate menus and allow printing attributes to be set.
For a printer to be used with the English language, a maximum of 26 text character keys are required, one for each letter of the alphabet. However, if the printer is to be used with other European languages, provision must be made to allow the user to specify letters with accents. For example, in the French language, “é” and “è” are required in addition to the ordinary “e”. In some European languages, a significant number of accented characters are required. This results in at least two problems.
Firstly, many machines are provided with additional text character keys to the standard 26 within the keyboard so as to enable the user to easily select the accented characters. This results in more space being taken up on the keyboard with text character keys, which means either a larger keyboard is required, which may not be convenient, particularly for a compact hand-held machine, and/or less space is available on the keyboard for function keys, which means that more keystrokes may be required to execute certain functions. Alternatively, the user may need to use a large number of keystrokes to access menus to enable selection of the required character, which is time consuming and complicated for the user.
Secondly, different accented characters are required for different European languages, which can mean that different keyboards are required for the same machine in dependence on the country in which it is to be sold. This makes manufacture more complicated and expensive. Furthermore, different memory chips and microprocessors may be required for different countries which provide the different menu sequences and store different sets of characters. Again, this complicates manufacture and increases production costs.
It would be desirable to provide a printer which enables a user to access accented characters in a number of European languages using a small number of straightforward keystrokes.